Interesting look at the world 20 years later!
I would honestly have expected Latin America in particular, but also Japan, Australia and New Zealand to heavily assist American recovery and rebuilding precisely because of North American natural resources.
Overall though I think you have painted a quite realistic picture of what the US looks like internally, as well as Europe and the former USSR. I do think the US has the capability to rise back to Great Power status given enough time - but I doubt the same for Russia, France and Britain.
One question- what’s the remaining nuclear capacity, if any, of the US, UK, and France? I’d have to think they each have SOMETHING left.
Based on the story so far, it doesn't seem un reasonable to assume that the US might have dozens of nuclear warheads at their disposal (the surviving aircraft carrier might have contributed some of them ?) Delivery systems and maintenance for the warheads would likely be more of problematic, but a small force of fission bombs delivered by aircraft would seem within the relm of the possible for the US IMHO. I'm thinking that even if replacing the tritium in more advanced weapons was impossible for the US that the fission primary stages could likely still be expected to produce some nuclear yield. From a practical perspective I can't see a surviving US using or threatening to use them in any circumstances other than an all out invasion of what is left of the continental US.
It also doesn't seem entirely out of the question to me that the US might entertain a trade of sorts with their (former ?) allies along the lines of providing samples of advanced nuclear weapons in return for significant foreign aid. Their (former ?) allies might also have concerns about "loose nukes" in the US and might be prepared to offer foreign aid in return for helping the US secure their stock pile ?
I'm also having a very hard time envisioning the US government being prepared to put much in the way of resources into maintaining a nuclear capability but they might not be prepared to completely rid themselves of such a capability either. A lot might depend on just how much documentation and knowledge survived the war and how complex any surviving weapons were. Depending on what actually survived I suppose in theory it might eventually be possible for the US to produce new nuclear warheads using fissile materials that were salvaged from pre war weapons, but I have my doubts that a US government in this fictional time line would want to do that.
As previously mentioned there is perhaps some possibility of the US keeping a modest fleet of SSBN's with un fired SLBM's going for some time after the war, but at some point I would expect they would become unsustainable or be seen as depreciating assets that could be traded for needed foreign aid while they still had some life left in them (perhaps the US might retain the actual nuclear weapons if only to provide a source of fissile materials for other possible future uses.)
Lots of possibilities for the US depending on exactly what happened during the war IMHO, but to recap I just don't see the US wanting to put much effort into maintaining a nuclear capability post war. The more I think about this, I suspect that fissile materials might be seen as very valuable assets by the US that could perhaps be traded for vital products and or perhaps horded for some future use. Conceivably there might also be some efforts made to consolidate any surviving tritium, and perhaps the US at some point might look to trade it for something very valuable ? (I believe tritum decays quite quickly.)
In the case of the UK and France the possibilities seem much more limited as they had far fewer weapons pre war, but it doesn't seem entirely out of the question they might each have a handful of nuclear warheads left (to recap a prior post of mine, maybe a surviving UK naval vessel brings back a few WE177's.)
Edit to add the political aspects of the relations between a post war US that has been largely devastated and allies that sustained much less devastation might be interesting as well. I could see Spain and Australia for example being very interested in getting their hands on some of the more advanced surviving US tech and likely having key products that the US needed. I wonder if NATO and ANZUS for example would be formally dissolved or somehow kept alive post war ?
Perhaps at some point in the distant future in this fictional time line , the US and some combination of Australia, Spain and perhaps Japan might work together to produce simple more or less "guaranteed to work" fission weapons using fissile material recycled from surviving US pre war nuclear weapons ? The US contribution might simply be handing over some pre war weapons in exchange for a smaller number of newer weapons, or depending on how much documentation and knowledge survived they might play a more active role in the project. Or the US might simply want more foreign aid and not want any new weapons or perhaps some combination of aid and new weapons might be wanted by the US.
